1. Field of the Invention
The invention relates to a novel apparatus and method for killing a cover crop by rolling and crimping.
2. Description of the Prior Art
Between 1990 and 2002, the number of U.S. cropland acres planted without tillage increased from 73.2 million acres to 103.1 million acres (CTIC, 2003). The use of cover crops has contributed to the overall success of conservation systems for many producers. Cover crops are increasingly being used to protect the soil from erosion during winter months, to enhance filtration and storage of winter rainfall, and reduce the negative effects of soil compaction (Reeves, 1994; Raper et al., 2000a; Raper et al., 2000b). Cover crops also increase the buildup of organic matter in the soil which leads to improved soil structure.
In this practice, the cover crop should be terminated prior to planting the cash crop to prevent the cover crop from using valuable spring moisture that could be used by the main cash crop after it has been planted. Several methods have been used for this purpose with the most common being the use of chemicals. This option is relatively fast and inexpensive and has quickly become the method of choice. However, planting after a chemical kill can sometimes be difficult if the cover crop has been allowed to become too large and lodged in multiple directions. This may hamper the ability of a planter with conservation tillage attachments from being successful in moving or cutting the residue and placing the seed in a proper soil furrow.
Another method that has often been used to terminate the cover crop is mowing. This option may also pose problems because cover crops can sometimes re-sprout and compete with the cash crop for available moisture and nutrients. Also, the unattached crop residue can make the planting operation difficult as row cleaners can become clogged with loose residue and require frequent cleaning.
Flattening and crimping cover crops is widely used in South America as a means to kill cover crops, and this practice is receiving increasing interest in North America. Implements for this purpose are usually round drums with attached blunt blades. As the device is rolled across the field, the blades crimp or crush the stalks of the cover crop, causing death of the plants. In this method, the purpose of the blades is to crimp or crush the stems of the cover crops and not cut them. If the stems are cut, the cover crops can re-sprout.
There are multiple benefits of rolling a cover crop (Ashford and Reeves, 2003). When the operation is conducted at the correct stage of plant growth, the roller is equally effective as chemicals at terminating the cover crop. Further, the energy required for rolling is significantly reduced from that of mowing, perhaps even as much as tenfold. Finally, a flat mat of cover crop is created that lays in the direction of travel. Producers using planters operating parallel or slightly off parallel to this direction have been very successful in obtaining proper plant establishment.
Despite these advances, some North American producers have reported problems with these machines when they have attempted to create or use rollers similar to those used in South America. The primary complaint has been the excessive vibration that the rollers transmit to the tractor. The most effective method of alleviating the vibration has been to reduce travel speed. However, most producers have found this to be an unacceptable solution, because at these low speeds the time needed to roll a large field is significantly greater than the time required to treat the same field with chemical sprays. For these and other reasons the need remains for an improved apparatus and method for rolling and crimping cover crops.